As a mounting method for mounting electronic parts and optical parts to a board, there are face-up alignment mounting and face-down alignment mounting. The face-up alignment mounting is a mounting method of image-recognizing a mounting position on a board and a front surface (top surface) of a mounting part, and moving the mounting part to the mounting position. The face-down alignment mounting is a mounting method of image-recognizing a mounting position on a board and a back surface (bottom surface) of a mounting part, and moving the mounting part to the mounting position. Because an image-recognition mechanism (a camera, a mounting part supporting apparatus, etc.) used in the face-up alignment mounting and the image-recognition mechanism (a camera, a mounting part supporting apparatus, etc.) used in the face-down alignment mounting are different in their arrangements and configurations, the face-up alignment mounting and the face-down alignment mounting are carried out using different mounting apparatuses.
FIG. 1 is a perspective view illustrating an outline structure of a face-up alignment mounting apparatus. A mounting board 1 is placed on an XY-stage 2, and an optical part 3A, which is a mounting part, is supported by a head 5 attached to a Z-stage 4. The head 5 is formed of a transparent material such as glass. A camera 6 is arranged above the Z-stage 4 so that a front surface (top surface) of the optical part 3A supported by the transparent head 5 can be image-recognized through a through hole 4a penetrating through the Z-stage 4. The camera 6 can carry out image recognition of a mounting surface of the mounting board 1 through the transparent head 5. The camera 6 is movable up and down by a Z-axis moving mechanism 7, and, thereby, the focal position of the camera 6 can be located at the front surface of the optical part 3 or at the mounting surface of the mounting board 1.
FIG. 2 is a perspective view illustrating an outline structure of a face-down alignment mounting apparatus. A mounting board 1 is placed on an XY-stage 12. A camera 16 is arranged above the position where a mounting board 1 is placed. The camera 16 is capable of image-recognizing the mounting surface of the mounting board 1 on an XY-stage 12. The camera 16 is movable up and down by a Z-axis moving mechanism 17, and, thereby, the focal position of the camera 16 can be placed at the mounting surface of the mounting board 1.
In the face-down alignment mounting apparatus illustrated in FIG. 2, a Z-stage 14 is provided at a position shifted from the camera 16, and a mounting part supporting head 15 is attached to the Z-stage 14. The Z-stage 14 is movable up and down by a Z-axis moving mechanism 18. A camera 19 is provided above the XY-stage 12 so that the back surface (bottom surface) of the optical part 20, which is a mounting part supported by the head 15, can be image-recognized by the camera 19. It should be noted that the face-down alignment mounting illustrated in FIG. 2 is a process for mounting the optical part 20 on the optical parts 3A and 3B.
Here, a description will be given, with reference to FIG. 3A through FIG. 8, of a process of mounting the optical parts 3A, 3B and 20 to the mounting board 1 using the mounting apparatuses illustrated in FIG. 1 and FIG. 2.
FIG. 3A is a plan view of the mounting board 1. FIG. 3B is a side view of the mounting board 1. Alignment marks 1a for position detection are provided to the mounting board 1. FIG. 4A is a plan view of the mounting board 1 after mounting the optical part 3B. FIG. 4B is a side view of the mounting board 1 after mounting the optical part 3B. FIG. 5A is a plan view of the mounting board 1 after mounting the optical part 3A. FIG. 5B is a side view of the mounting board 1 after mounting the optical part 3A. FIG. 6A is a plan view of the mounting board 1 after mounting the optical part 20. FIG. 6B is a side view of the mounting board 1 after mounting the optical part 20. FIG. 7 is a flowchart of a process of mounting the optical parts 3A and 3B on the mounting board 1 using the face-up alignment mounting apparatus illustrated in FIG. 1. FIG. 8 is a flowchart of a process of mounting the optical part 20 on the mounting board 1 using the face-down alignment mounting apparatus illustrated in FIG. 2.
In the mounting process illustrated in FIG. 7, the optical parts 3A and 3B are mounted to the mounting board 1. First, in step S1, the alignment patterns 1a provided on the mounting surface of the mounting board 1 placed on the XY-stage 2 are detected by image recognition by the camera 6. At this time, the image recognition by the camera 6 is carried out by the picture of the mounting surface of the mounting board 1 taken through the through hole 4a of the Z-stage 4 and the transparent head 5.
Next, in step S2, a position where the optical part 3B is to be suction-attached and held by the head 5 is determined. The optical part 3B is accommodated in a part tray (not illustrated in the figure) provided on the XY-stage 2, and the suction-attaching position of the optical part 3B is detected by image-recognizing the optical part 3B by the cameral 6 by moving the part tray under the head 5 by driving the XY-stage 2.
Subsequently, in step S3, the optical part 3B is suction-attached and held by the head 5 in accordance with the suction-attaching position detected in step S2. Then, the mounting board 1 is located under the head 5 again by driving the XY-stage 2. Then, in step S4, the mounting surface of the mounting board 1 is image-recognized by the camera 6, and the mounting position of the optical part 3B is computed. Then, in step S5, the XY-stage 2 is moved so that the mounting position computed is located under the optical part 3B suction-attached by the head 5, and the optical part 3B is mounted on the mounting board 1 by moving the head 5 downward by driving the Z-stage 4. FIGS. 4A and 4B illustrate a state where the optical part 3B is mounted on the mounting board 1. Then, in step S6, the position where the optical part 3B is mounted is detected based on the image recognition of the camera 6.
Next, in step S7, the suction-attaching position of the optical part 3A is detected. The optical part 3A is accommodated in a part tray (not illustrated in the figure) provided on the XY-stage 2, and the suction-attaching position of the optical part 3A is detected by image-recognizing the optical part 3A in the part tray by the cameral 6 by moving the part tray under the head 5 by driving the XY-stage 2.
Then, in step S8, the optical part 3A is suction-attached and held by the head 5 based on the suction-attaching position detected in step S7. Then, the mounting board 1 is located under the head 5 again by driving the XY-stage 2. Then, in step S9, the mounting surface of the mounting board 1 is image-recognized by the camera 6, and the mounting position of the optical part 3A is computed. At this time, the mounting position of the optical part 3A is computed based on the position of the optical part 3A suction-attached to the head 5 and the position of the optical part 3B on the mounting board 1. Then, the XY-stage 2 is moved so that the mounting position computed in step S9 is located under the optical part 3A suction-attached by the head 5, and the optical part 3A is mounted on the mounting board 1 by moving the head 5 downward by driving the Z-stage 4. FIGS. 5A and 5B illustrate a state where the optical parts 3A and 3B are mounted on the mounting board 1.
According to the above-mentioned process, the optical parts 3A and 3B are mounted on the mounting board 1. Because the optical part 3A is mounted based on the result of detection of the position of the optical part 3B, which is mounted first, the optical parts 3A and 3B can be mounted with a highly accurate positional relationship.
After mounting the optical parts 3A and 3B to the mounting board 1, the process proceeds to a mounting process of the optical part 20. Here, the optical part 20 has on its back surface (bottom surface) functional parts, which cooperate with the optical parts 3A and 3B mounted previously, and the optical part must be arranged on the optical parts 3A and 3B so that the optical parts 3A and 3B and the functional parts are in an aligned state. Thus, a mounting operation of the optical part 20 to the mounting board 1 is performed in the mounting process illustrated in FIG. 8 using the face-down alignment mounting apparatus while image-recognizing the back surface (bottom surface) of the optical part 20. Therefore, after mounting the optical parts 3A and 3B to the mounting board 1, it is necessary to move the mounting board 1 to the XY-stage 12 of the face-down alignment mounting apparatus.
After moving and placing the mounting board 1 onto the XY-stage 12 of the face-down alignment mounting apparatus, first in step S11, the optical part 20 is suction-attached to and held by the head 15. The optical part 20 is accommodated in the part tray (not illustrated in the figure) provided on the XY-stage 12, and the XY-stage 12 is driven to move the part tray under the head 15 to hold the optical part 20 by the head 15. In this case, the position of the optical part 20 accommodated in the part tray has been image-recognized previously by the camera 16 and stored as image data, and the position of the optical part 20 can be detected from the image data as a result of the image-recognition and the optical part 20 can be held by the head 15.
After holding the optical part 20 by the head 15, the mounting board 1 is image-recognized, in step S12, by the camera 16 to detect the position of the optical part 3A previously mounted. Further, in step S13, the position of the optical part 3B previously mounted is also detected.
Subsequently, in step S14, the back surface (bottom surface) of the optical part 20 held by the head 15 is image-recognized to detect the present holding position of the optical part 20. Then, in step S15, the mounting position of the optical part 20 is computed based on the result of detection of the optical parts 3A and 3B in steps S12 and S13. Then, in step S16, the XY-stage 12 is driven to move the XY-stage 12 so that the computed mounting position is aligned with the optical part 20 held by the head 15, and the Z-stage 14 is moved downward to mount the optical part 20 to the mounting board 1. At this time, as illustrated in FIGS. 6A and 6B, the functional parts 20a of the optical part 20 is in an aligned state with the optical parts 3A and 3B.
As mentioned above, according to the conventional mounting method, face-up alignment mounting of the optical parts 3A and 3B is performed first, and, subsequently, face-down alignment mounting of the optical parts 20 is performed. That is, although the mounting apparatuses are different, the positions of the mounting board 1 and the optical parts 3A and 3B are image-recognized by the cameras 6 and 16 from the upper side and the back surface of the optical part 20 is image-recognized by the camera 19, and the mounting position of the optical part 20 is determined according to the thus-acquired image-recognition data.
Here, there is suggested a chip bonding apparatus which, when mounting a single semiconductor chip to a board according to face-down alignment mounting, performs positioning of the semiconductor chip by image-recognizing the back surface of the semiconductor chip by one camera and image-recognizing the mounting surface of the board by another camera (for example, refer to Japanese Laid-Open Patent Application No. 9-8104).
As mentioned above, in the case where after mounting a plurality of first mounting parts (corresponding to the optical parts 3A and 3B) to a board according to face-up alignment mounting, a second mounting part (corresponding to the optical part 20) is mounted to the board (corresponding to the mounting board 1) according to face-down alignment mounting, the plurality of mounting parts can be mounted on the board with high positional accuracy with each other and the second mounting part can be accurately positioned to the plurality of first mounting parts on the board. However, because there is a manufacturing variation in the position of the functional parts in the second mounting part, even if the relative position accuracy is raised, there may be a problem in that the first mounting parts cannot be accurately positioned to the respective functional parts of the second mounting part having variation in the relative positions.
Additionally, when performing face-down alignment mounting, there is a problem in that the camera for image-recognizing the mounting surface of the board and the camera for image-recognizing the back surface of the part are different cameras, and it is difficult to prevent an offset even if the positions and angles of the cameras are accurately corrected and the results of the image-recognition results are combined.
Further, if the resolution of the cameras is increased in order to perform highly accurate image-recognition, the view is narrowed and it becomes difficult to recognize the position of the part accommodated in the part tray. Thus, if a wide-view camera for recognizing the part positions is provided separately, it invites an increase in size and cost of the mounting apparatus.